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Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 31 |
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@@ -9656,6 +9656,37 @@ the equal function instead. In addition to storing key-value pairs, a hash table can have a piece of information associated with it, called the user data. +.SS Function group-by + +.TP +Syntax: + + (group-by <func> <sequence> . <options>) + +.TP +Description: + +The group-by function produces a hash table from <sequence>, which is a +list or vector. Entries of the hash table are not elements of sequence, +but lists of elements of <sequence>. The function <func> is applied toe +each element of <sequence> to compute a key. That key is used to determine +which list the item is added to in the hash table. + +The trailing arguments <options>, if any, consist of the same keywords +that are understood by the hash function, and determine the properties +of the hash. + +.TP +Example: + +Group the integers from 0 to 10 into three buckets keyed on 0, 1 and 2 +according to the modulo 3 congruence: + + (group-by (op mod @1 3) (range 0 10))) + + -> #H(() (0 (0 3 6 9)) (1 (1 4 7 10)) (2 (2 5 8))) + + .SS Functions make-similar-hash and copy-hash .TP |